Viscosity responsive device



Dec. 6, 1960 J. G. JANSSON 2,962,891

VISCOSITY RESPONSIVE DEVICE Filed Aug. 1, 1958 I- I I I I I I I."UII-aI-II menial d6. Qfmasozv United States Patcht O 2,962,891vrscosn'r RESPONSIVE DEVICE Johannes Gerhard Jansson, Stockholm, Sweden,assignor to Aktiebolaget A. Ekstroms Maskinalfar, Stockholm, Sweden, aSwedish company Filed Aug. 1, 1958, Ser. No. 752,638 Claims priority,application Sweden Aug. 7, 1957 11 Claims. (Cl. 73-55) The inventionrelates to a method for utilizing the friction losses of a mediumflowing through a pipe for adjusting the consistency of the medium andis substantially characterized in that the diflference in pressurerelative to the flow between the inlet and outlet end of the pipe ismeasured and controls a device for adjusting the consistency of themedium.

The invention also relates to a device which according to the methodautomatically adjusts the consistency of the medium at any moment. Suchdevices are particularly capable of use in cellulose industries forautomatic control of the pulp concentration.

According to the invention a unit comprising two rigid plates and aninterjacent diaphragm is secured to form the partition wall between theinlet and outlet of a pipe loop through which the medium is caused toflow, for sensing the difference in pressure occurring at this point andtransmitting the same to an outside adjustment device. The casingcontaining the inlet and outlet can also be designed in such a way thatthe flowing medium is caused to contact the diaphragm unit from both itssides, the plates being arched at least in the direction of flow inorder to obtain an extra pressure component in addition to thedilference in pressure owing to the friction losses. The extra pressureis obtained as a reaction force according to the same physical laws thatare valid for the wing of an aeroplane or a blade of a turbine.

The diaphragm plates may be designed and turned in various ways if theplates on both sides of the plane running through the fastening edge ofthe diaphragm are asymmetrically arched. The plates are, however,preferably arched or bulged in the same direction, the curving of theplates individually being allowed to be of various sizes. The curving ofone or both plates may also be asymmetrical in relation to the centralaxis running through the diaphragm transversally to the direction offlow. It becomes evident that through mounting the diaphragm unit in thepartition wall with the convex side being turned to the outlet and inletends, respectively, an effect is obtainable which, as desired, eitherincreases or reduces the diiference in pressure.

The purpose of this increase or reduction is to obtain an optimallysensitive, secure, rapid and uniform regulation for a wide range ofvariations of the consistency of the medium. Supposing the diaphragmplaced between the inlet and outlet of the friction loop with the convexside of the plate assembly facing the inlet side, the diaphragm will, aslong as the consistency desired is prevailing, remain in a medianposition balanced by the inlet and outlet pressures as well as thereaction force acting upon the curved surfaces of the plate assembly andif required a biasing force, such as a spring.

If the consistency increases, thereby increasing the pressure difierencebetween the inlet and the outlet, the diaphragm will move towards theoutlet side against the biasing force. At the same time, however, thevelocity of the medium decreases and the reaction force acting on theplate assembly will diminish, allowing the dia r 2,962,891 i PatentedDec. 6, 1960 phragm to move still more towards the outlet sideincreasing the impulse to the external adjustment device.

If, on the other hand, the consistency of the medium decreases thepressure difference will be reduced and thus the diaphragm by thebiasing force will move over towards the inlet side. Simultaneously thevelocity of the medium increases and also the reaction force on theplate assembly, moving the diaphragm still more towards the inlet.

It is thus seen that the form of the plate assembly generally amplifiesthe movements of the diaphragm and thus the impulses to the externaladjustment device.

In the following description where it is referred to the accompanyingdrawings, a preferable embodiment is described in detail.

Fig. 1 of the drawings shows a schematic vertical view of the adjustmentdevice according to the invention as a section along the line I I ofFig. 2.

Fig. 2 shows a schematic horizontal view of the device as a sectionalong the line 11-11 of Fig. 1.

Fig. 3 shows in enlarged scale a longitudinal section through thediaphragm unit according to the invention along the line IIII of Fig. l,and

Fig. 4 shows a cross section through the diaphragm unit along the lineIV-IV of Fig. 3.

In Fig. 2 is shown a pipe socket 1 intended to be inserted in a pressurepipe of a pulp pump from which socket starts a loop 2 having an inlet 3and an outlet 4, to the partition wall of which a diaphragm unit 5 issecured which is described more specifically later on. By means of aliquid pump 6 being placed in the inlet 3 of the pipe a portion of thepulp passing through the socket 1 is shunted through the loop 2. Owingto the friction losses of the liquid occurring in loop 2 a lowerpressure is efiected at the outlet 4 than at the inlet 3, saiddifference in pressure being dependent on the viscosity of the liquidand thus adapted to be used for adjusting the same, i.e. in this casethe pulp concentration.

The difference in pressure is sensed by the above diaphragm unit 5arranged in the partition wall, said diaphragm unit comprising adiaphragm 7 (see Figs. 3 and 4) fastened up at its edge and clampedbetween the two rigid plates 8 and 9.

In the embodiment shown the plates are arched or bulged in the samedirection, in the direction of flow of the liquid as well as in thedirection normal to the direction of flow, the convex side of the unit 5being turned to the inlet 3. Furthermore, the curving of the plates isof difierent size and also individually asymmetrical in relation to thetransverse axis of the diaphragm axis 5. The input end of plate 8 isfastened to a shaft 10 which is pivotally arranged on the pipe casing,the outer end of said shaft, for example, by means of a lever 11 forcontrolling a conventional device for adjusting the pulp concentration.

Owing to the fact that the casing containing the inlet and outlet of theloop is designed in such a way that the liquid when flowing in and outis caused to contact the arched diaphragm unit 5 from both its sides, anextra pressure component is obtained which in the embodiment shownproduces an elfect in the opposite direction of the dilference inpressure due to the friction losses occurring in the coil 2, i.e. thediflerence in pressure is reduced. On the lever 11 a spring 12 (Fig. 2)may be arranged to counteract the diaphragm movement, said movementthus, as desired, being modifiable through changing the tension of thespring.

Of course, the invention is not limited to the embodiment shown. Thediaphragm unit 5, for example, may be turned in the opposite way, i.e.the convex side directed to the outlet 4, through which measure insteadof a reduction an increase of the difference in pressure is effected.For adjusting to a special purpose, it is further possible to modify thecurving of the plates 8 and 9 in VaIIOHS ways.

What I claim is:

l. A device for continuously determining the consistency of a mediumflowing in a conduit comprising a loop of pipe extending from saidconduit andreturning thereto, comprising a partition wall separating theinlet and outlet of said pipe loop through which the medium flows formedby a diaphragm unit, said diaphragm unit sensing the difference inpressure between said inletand outlet, the central portion of saiddiaphragm unit being clamped between two rigid plates and secured to a,shaft to operate an adjustment device.

2. A device according, to claim 1', including a casing containing theinlet and outlet designed in such a way that the medium, during itsflow, is caused'to contact the diaphragm unit from both its sides, theplates being arched at least in the direction of flow in order to modifythe pressure component of the-flowing medium in addition to thedifference in pressure caused by the friction losses.

3. A device according to claim 2, in which the plates are arched in thesame direction;

4. A device according to claim 3, in which. the radii of curvature ofthe plates are of. different length.

5. A device according to claim 4, in which the curvature of one plate isasymmetrical} in relation to an axis running through the diaphragmtransversely of the direction of flow.

6. A device according to claim 3, in which the convex side ofthediaphragm and plates unit is turned to the inlet end in order to effecta pressure component reducing the difference in pressure.

7. A device according to claim 3, in which the convex side of thediaphragm and plates unit is turned to the outlet end in order to efiecta pressure component increasing the difference in pressure.

8. A device according to claim 3, in which the plates are also arched ina direction transversally to the direction of flow.

9. A device according to claim 1, in. which the one plate on its oneside is fastened to a pivotally arranged shaft carrying a lever actingupon an outside adjustment device.

10. A device according to claim 9, including an adjustable spring actingupon the lever and hindering the movement of the diaphragm.

11. A device to continuously determine the viscosity of a fluid passingthrough a primary conduit, comprising a branch connection to saidconduit, a branch conduit forming a loop having a first end extendingfrom said branch connection and a second end returning thereto, meansfor forcing a flow of fluid from said primary conduit into said firstend of said branch conduit, a flexible diaphragm unit forming a commonwall portion of said first and second ends of said branch conduit, atleast one plate secured to said diaphragm, a pivot secured to said platenear one end thereof, said pivot extending through the Wall of saidconduit, and means mounted exteriorly of said conduit whereby theviscosity of the fluid in the conduit may be determined by the positionof said means.

References Cited in the file of this patent UNITED STATES PATENTS

